Field of the Invention
The present disclosure relates to a method and a circuit for driving a touch sensor and a display device using the same.
Discussion of the Related Art
User interfaces (UIs) are configured to allow users to communicate with various electronic devices and to easily and comfortably control the electronic devices as they desire. Examples of UIs include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology has continuously expanded to increase user's sensibility and handling convenience. UIs have been recently developed to include touch UIs, voice recognition UIs, 3D UIs, and the like.
A touch screen may be implemented as capacitive touch sensors. In addition, the touch screen may be implemented as resistive touch sensors, surface acoustic wave (SAW) type touch sensors, pressure type resistive touch sensors, infrared type touch sensors, and the like. The most important factor to determine a performance of the touch screen is a signal to noise ratio (often abbreviated to “SNR” or “S/N”). When noise introduced into a touch screen decreases, a value of a SNR increases. Hence, an operation margin of a touch driving circuit can increase, and sensitivity of touch sensing can be improved.
In order to improve the SNR, a method for accurately measuring the noise introduced into the touch sensor is important. Because the noise introduced into the touch sensor varies in real time depending on a surrounding environment, noise should to be continuously measured. A method for improving the SNR when a frequency of a touch sensor driving signal involves changing to avoid a frequency associated with high noise. An example of such method includes changing a frequency of a touch sensor depending on a level of noise, which is disclosed in Korean Patent Application Publication No. 10-2012-0057009 (Jun. 5, 2012) corresponding to the present applicant.
A method for measuring noise of a touch sensor may measure noise of a touch sensor at a particular position in an entire touch screen. However, this method cannot measure noise at positions other than a previously determined position. As a result of analyzing a performance of a touch screen in various product groups, noise of touch sensors appears in various forms in the entire touch screen.